I have a mossberg 500. Full stock. Recently added a flashlight up front. (newer LED lights are fantastic)

I have a Convoy S2+ on one of my shotguns and a BLF A6 on the other. You're right on these new LED lights, particularly the ones with a CREE LED and a good, solid driver with multiple options. The Convoy puts out 500 lumens and the BLF puts out 1200+ (maybe as high as 1600 depending on the battery). Both use 18650 batteries. Just installed a Convoy S2+ on my Sub 2K as well.

As a side note, I carry a Convoy S2+ on-duty because it has a very powerful strobe feature. Great for lighting someone up and making them see spots for a few seconds.